In the case of a known wiper lever, the supporting element of the wiper blade is supposed to guarantee the most uniform possible distribution of wiper blade application force originating from the wiper arm on the window over the entire wiper field being covered by the wiper blade. Because of a corresponding curvature of the unstressed supporting element—i.e., when the wiper blade is not adjacent to the window—the ends of the wiper strip that are applied completely to the window during wiper blade operation are stressed by the then tensioned supporting element on the window, even if the curvature radii of spherically curved vehicle windows change with every wiper blade position. The curvature of the wiper blade must therefore be somewhat greater than the greatest curvature measured in the wiper field on the to-be-wiped window. The supporting element thereby replaces the expensive supporting bracket design, which is required to distribute the application force, with two spring rails arranged in the wiper strip, which are used for transverse reinforcement of the rubber elastic wiper strip, as is the practice with conventional wiper blades (German Printed Specification 1247 161).
In a known wiper lever in accordance with the species of PCT/DE01/04307 the cap covering the articulated connection between the wiper arm and the wiper blade is locked exclusively by friction with the wiper blade. A special fixation of the cap in the longitudinal direction of the wiper blade is not provided. In order to keep the assembly time of the cap on the wiper blade—including the required determination of position—as short as possible, the dimension of the passage opening in the longitudinal direction of the wiper blade must be provided with a high plus tolerance so that the required smooth-running oscillating movement between the wiper arm and the wiper blade is not impaired. The gaps thereby yielded between wiper arm and the edge of the passage opening in the cap lead to undesired air stream noise and also interfere with the harmonic transition between wiper blade and wiper arm in the area of the articulated connection that is striven for with the arrangement of the cap.